JP2000354366A - Dc-dc converter and electronic apparatus with this built- in dc-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to supply power stably to a second load by supplying power from a rectifier and filter means connected to a current-limiting means to a first load that is less affected by voltage fluctuation and by supplying power from a rectifier and filter means not connected to a current-limiting means to the second load that is largely affected by the voltage fluctuation. SOLUTION: A rectifier and filter means 14 comprises a series connected unit 7 made up of a rectifier diode 9 and a capacitor 11, and another series-connected unit 15 made up of a rectifier diode 8, a current-limiting means (a resistor 16) and a capacitor 10. A light source 12 that is less affected by voltage fluctuation is connected to the series-connected unit 15, and a measuring system 13 that is largely affected by the voltage fluctuation to the series-connected unit 7. Here, the electric potential at Point A becomes equal to the terminal voltage of the capacitor 10 plus the portions of the voltage drop caused by the rectifier diode 8 and resister 16. For the terminal voltage drop of the capacitor 11 caused by the power consumption of the measuring system 13, the capacitor 11 is charged at the time when its terminal voltage becomes equal to or lower than the terminal voltage minus the portion of the voltage drop caused by the rectifier diode 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC-DC converter for converting a DC input voltage into a plurality of DC output voltages via an AC converter for converting the DC input voltage to an AC voltage, and a DC-DC converter for converting the DC input voltage into a plurality of DC output voltages.
The present invention relates to an electronic device incorporating a DC converter, and more particularly to a DC-DC converter capable of supplying a stable DC output voltage even when the DC input voltage fluctuates, and an electronic device incorporating the DC-DC converter.

[0002]

2. Description of the Related Art A DC-DC converter for converting a DC input voltage into a plurality of DC output voltages via an AC converter for converting the DC input voltage into an AC voltage.
Various types of DC converters and electronic devices incorporating the DC-DC converter have been proposed or put into practical use.

[0003] For example, an appropriate light source such as an infrared light emitting diode practically used in the field of photographic cameras projects infrared light toward a subject, and reflects infrared light reflected from the subject with a suitable light receiving sensor. A so-called active-type distance measuring device that measures the angle of the infrared reflected light by receiving light at the above and obtains distance information from the measurement result to the subject is a DC-DC converter and a DC-D converter as described above.
It is well known as an electronic device incorporating a C converter.

[0004] This active type distance measuring apparatus has a DC-DC
Among a plurality of DC output voltages output from the converter, one DC output voltage is used as a power source of a light source for infrared light projection.
The other DC output voltage is used as a power supply of a measurement circuit system for performing a process of receiving infrared reflected light.

[0005] In addition, since the infrared reflected light from the subject is usually very weak, in order to brighten the light emitted from a light source such as an infrared light emitting diode, as much current as possible is passed through the light source, and at the same time, the light is reflected from the subject. Measurement of infrared reflected light of
At this time, in a measuring circuit system for measuring and processing the infrared reflected light, it is desired that the power supply voltage be stabilized in order to perform an accurate distance measuring operation.

FIG. 4 is an electric circuit diagram of an example of a conventional active distance measuring apparatus in which the above-mentioned stabilization of the power supply voltage is taken into consideration.

In this conventional example, a DC input voltage output from a power supply battery 1 as a DC power supply is converted into an AC voltage by intermittently supplying the DC input voltage to a boosting inductor 4 by controlling the on / off operation of a transistor 3 as a switch means. The AC converter 2 is composed of a plurality of series-connected bodies 6 and 7 in which rectifier diodes 8 and 9 and capacitors 10 and 11 are connected in series, respectively. , 11 to output a plurality of DC output voltages, a light source (infrared light emitting diode) 12 for infrared projection, which is a load, and a circuit for measuring infrared reflected light (for measuring infrared reflected light). IC) 13.

In FIG. 4, when the transistor 3 of the AC conversion means 2 is turned on and off, the output voltage of the power supply battery 1 which is a DC power supply is intermittently supplied to the boost inductor 4.
As a result, an AC high voltage is generated at point A in the drawing, which is the output terminal of the AC conversion means 2.

The AC high voltage generated at the point A is supplied to the series-connected bodies 6 and 7 of the rectifying / smoothing means 5, so that the capacitor 10 is connected via the diode 8 and the capacitor 11
Is charged via the diode 9.

The charged voltage of the charged capacitor 10 is:
When supplied to a light source (infrared light emitting diode) 12 for infrared light projection, it functions as a driving power source for the light source 12;
The charged voltage of the charged capacitor 11 is supplied to an infrared reflected light measurement circuit system (infrared reflected light measurement IC) 13 to function as a drive power supply for the measurement circuit system 13.

For this reason, the supply of the drive power supply voltage to the light source 12 and the measurement circuit system 13, which are loads, is performed from the capacitors 10 and 11, respectively, that is, the power supply system for the load is configured separately. Therefore, by stabilizing the power supply voltage supplied to the load, the capacity of the capacitors 10 and 11 is set to a capacity capable of supplying sufficient power for the operation of the light source 12 and the measurement circuit system 13 which are loads connected to each other. I can plan.

Various other means are known for stabilizing the power supply voltage.
Japanese Patent Application Publication No. 52-52204 discloses that the secondary side output obtained by switching the primary side of a transformer is fed back so that a stable output can be obtained against a sudden change in the load of the DC-DC converter. Circuit means for controlling the power supply and supplying a stable output to the secondary side.

[0013]

In the active type distance measuring apparatus having the structure shown in FIG. 4, supply to the infrared light source 12 is also required in order to increase the distance to the subject from which the distance can be measured. If the current is further increased, the power supply battery 1 and the DC-D
When the capacity of the C converter is insufficient, the power supply from the DC-DC converter is performed only to the capacitor 10 serving as the power source of the light source 12 for infrared projection, and the power source of the measurement circuit system 13 for the infrared reflected light Power is not supplied to the capacitor 11 which is to be turned off, and the voltage of the capacitor 11 may decrease.

Briefly, when the light emitting operation of the light source 12 and the distance measuring operation by the measuring circuit system 13 are performed to perform the distance measuring operation, the capacitors 1 functioning as the respective power supplies are provided.
0 and the charge of the capacitor 11 are consumed.

At this time, since the current consumption of the light source 12 is larger than the current consumption of the measurement circuit system 13, the capacitor 10
Will be consumed more than the consumption of the charge of the capacitor 11. Therefore, the potential of the point A which is the output terminal of the AC conversion means 2 depends on the influence of the capacitor 10 which consumes a large amount of the charge. As a result, the potential becomes the potential V2 obtained by adding the voltage drop by the rectifier diode 8 to the terminal voltage of the capacitor 10.

Therefore, when the performance of the power supply battery 1 is not sufficient, such as when the performance of the power supply battery 1 is deteriorated at a low temperature, FIG.
In the conventional example shown in (1), it is difficult to quickly replenish the charge of the capacitor 10 consumed by the previous light emitting operation, that is, it is difficult to maintain the terminal voltage of the capacitor 10 at a desired value. The potential at the point A decreases following the previous light emitting operation.

Incidentally, the terminal voltage of the capacitor 11 also drops due to the power consumption by the measuring circuit system 13, similarly to the terminal voltage of the capacitor 10. On the other hand, the charging operation for compensating for the voltage drop of the capacitor 11 is performed by the terminal of the capacitor 11. If the voltage does not fall below the voltage obtained by subtracting the voltage drop by the rectifier diode 9 from the potential at the point A, the operation is not performed.

In other words, in the case of the conventional example shown in FIG.
When the potential at the point A decreases, the terminal voltage of the capacitor 11 continues to decrease to a voltage obtained by subtracting the voltage drop of the rectifier diode 9 from the reduced potential at the point A.

When the voltage of the capacitor 11 decreases, the operation of the measuring circuit system 13 is greatly affected. In some cases, the measuring circuit system 13 malfunctions, such as outputting erroneous distance information, and performs an accurate distance measuring operation. It is not possible to perform the measurement, and it is conceivable that the distance measurement accuracy is significantly reduced.

That is, even if the power supply system is separated for each load and a capacitor is connected to each load as in the conventional configuration shown in FIG. 4, the energy consumption state of the load and the power supply capability of the power supply battery to the capacitor can be reduced. Depending on the setting situation, a voltage fluctuation or a voltage drop of one capacitor may be directly reflected on another capacitor, and in such a case, a desired operation cannot be obtained.

Although it is possible to cope with the above-mentioned inconvenience by adopting a capacitor having a sufficient capacity, in such a case, the shape of the capacitor is inevitably increased in size, and in recent years, the miniaturization of various electronic devices is rapidly progressing. It is becoming more difficult to implement the above measures from the current situation, and the camera incorporating the active type distance measuring device exemplified above is no exception.

In addition, limiting the energy consumption state of the load, that is, limiting the current consumption of the infrared light source for light emission to suppress the occurrence of erroneous distance measurement operation in the case of the distance measuring device described above, is also possible. In this case, it is possible to cope with the inconvenience, but in this case, even if there is enough battery capacity, the current consumption is suppressed, which causes a new inconvenience that the distance to the subject for which distance measurement can be performed is always small. become.

On the other hand, the circuit means for improving the performance of the DC-DC converter disclosed in Japanese Patent Application Laid-Open No. 5-49252 is also designed to perform a sufficient boosting operation until the battery performance is reduced. Is complicated,
In addition, it has been difficult to employ a large-sized and similarly miniaturized camera.

Considering the degree of influence of the power supply voltage drop or fluctuation in the power supply of the infrared light source for infrared projection or the power supply of the circuit system for measuring infrared reflected light on the distance measuring operation itself, it will be described in detail. Needless to say, voltage fluctuations in the power supply of the measurement circuit system have a large effect on the distance measurement operation, and specifically, greatly affect the distance measurement performance of the distance measurement device. There is a possibility that an erroneous ranging operation may occur regardless of the distance.

In other words, in an electronic device having a built-in DC-DC converter that outputs a plurality of DC output voltages, the degree of influence on voltage fluctuation and voltage drop among a plurality of loads to which the plurality of DC output voltages are supplied is described. However, when there is a difference, there is an inconvenience that the occurrence of voltage fluctuation or the like may adversely affect the main operation.

The present invention has been made in consideration of the above-described disadvantages, and has a DC-DC power supply that can stably supply power to a power supply destination that is greatly affected by voltage fluctuations and the like.
An object of the present invention is to provide a DC converter and an electronic device incorporating the DC-DC converter.

[0027]

SUMMARY OF THE INVENTION DC-DC according to the present invention
The converter includes an AC conversion unit that converts a DC input voltage into an AC voltage and outputs the AC voltage, and a plurality of series-connected bodies in which a rectifier diode and a capacitor are connected in series, and the series connection is performed by supplying the AC voltage. Rectifying and smoothing means for outputting a plurality of DC output voltages from each capacitor of the body, and in series with at least one rectifying diode of a plurality of serially connected bodies forming the rectifying and smoothing means, and in series with the rectifying diode. Current limiting means connected to a position where the output path of the DC output voltage of the connected capacitor is not formed.

Thus, the fluctuation of the DC voltage output caused by the operation of the load receiving the DC output voltage from the rectifying and smoothing means connected to the current limiting means is suppressed. The effect of the voltage fluctuation of the DC voltage output based on the operation of the load is not directly reflected on other loads, and as a result, the power supply from the rectifying and smoothing means to which the current limiting means is connected is affected by the voltage fluctuation and the like. The first rectifying and smoothing means, to which the current limiting means is not connected, supplies power to the second load which is greatly affected by voltage fluctuations and the like.
DC-DC that can supply stable power to the load
You can get a converter.

An electronic device incorporating a DC-DC converter according to the present invention comprises an AC converter for converting a DC input voltage into an AC voltage and outputting the AC voltage, and a plurality of series-connected bodies in which a rectifier diode and a capacitor are connected in series. Rectifying and smoothing means for outputting a plurality of DC output voltages from the respective capacitors of the series-connected body by supplying the AC voltage, and at least one of the plurality of series-connected bodies forming the rectifying and smoothing means. A DC-DC converter having current limiting means connected in series with one rectifier diode and at a position not forming an output path of a DC output voltage of a capacitor connected in series with the rectifier diode; The rectifying / smoothing means to which the means is connected is connected to a first load which is less affected by voltage fluctuation and the like.

Thus, the fluctuation of the DC voltage output caused by the operation of the load receiving the DC output voltage from the rectifying and smoothing means to which the current limiting means is connected is suppressed. It is possible to stably supply power to the second load that is greatly affected by voltage fluctuations and the like from the unconnected rectifying and smoothing means, and it is possible to obtain an electronic device that can expect stable load operation.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the first aspect of the present invention, there is provided an AC converter for converting a DC input voltage into an AC voltage and outputting the AC voltage, and a plurality of series-connected bodies in which a rectifier diode and a capacitor are connected in series. Rectifying / smoothing means for outputting a plurality of DC output voltages from the respective capacitors of the series-connected body when the AC voltage is supplied, and a plurality of series-connected bodies forming the rectifying / smoothing means. A DC-DC converter comprising: current limiting means connected in series with at least one rectifier diode and at a position not forming an output path for a DC output voltage of a capacitor connected in series with the rectifier diode. And a voltage change of the DC output voltage generated based on the operation of the load receiving the DC output voltage from the rectifying and smoothing means to which the current limiting means is connected. Such an action and the like can be suppressed.

According to a second aspect of the present invention, the current limiting means in the DC-DC converter according to the first aspect is constituted by a resistor, and has the same operation as the first aspect.

According to a third aspect of the present invention, in the DC-DC converter according to the first aspect, the current limiting means is turned off in response to the operation of consuming the charge of the capacitor to which the DC-DC converter is connected. And a transistor which is turned on when the capacitor is charged, and has the same function as the first aspect of the present invention.

According to a fourth aspect of the present invention, in the DC-DC converter according to the first to third aspects, the AC converting means includes a step-up inductor to which a DC input voltage is applied, and an on / off operation. By doing so, the switching means for intermittently applying the DC input voltage to the boosting inductor is provided, and has the same operation as the first aspect of the present invention.

According to a fifth aspect of the present invention, in the DC-DC converter according to the fourth aspect, the on / off operation of the switch means is controlled by detecting a voltage fluctuation of a capacitor to which the current limiting means is not connected. It is configured to include a control means, and has the same operation as the invention according to claim 4.

According to a sixth aspect of the present invention, there is provided the DC-DC converter according to the fifth aspect, wherein the high potential side terminal of the capacitor to which the current limiting means is not connected and the current limiting means are connected. And a resistor connected between the high-potential side terminal of
It has the same function as the invention described in claim 4.

According to a seventh aspect of the present invention, there is provided an AC conversion means for converting a DC input voltage into an AC voltage and outputting the converted AC voltage, and a plurality of series-connected bodies in which a rectifier diode and a capacitor are connected in series. A rectifying / smoothing unit that outputs a plurality of DC output voltages from each capacitor of the series-connected body by being supplied with the AC voltage, and at least one of a plurality of series-connected units that form the rectifying / smoothing unit. DC having current limiting means connected in series with a rectifier diode and at a position where an output path for a DC output voltage of a capacitor connected in series with the rectifier diode is not formed
A first rectifying / smoothing unit which has a built-in DC converter and is connected to the current limiting unit and which is less affected by voltage fluctuation and the like;
An electronic device is configured by connecting a load, and suppresses a voltage fluctuation or the like of the DC output voltage generated based on an operation of a load receiving a DC output voltage from a rectifying and smoothing unit to which a current limiting unit is connected. This has the effect of stably supplying power to the second load, which is greatly affected by voltage fluctuations and the like.

According to an eighth aspect of the present invention, the current limiting means in the electronic device according to the seventh aspect is constituted by a resistor, and has the same operation as the seventh aspect of the invention.

According to a ninth aspect of the present invention, in the electronic device according to the seventh aspect, the current limiting means is turned off in response to the operation of consuming the charge stored in the capacitor connected thereto. It is constituted by a transistor which is turned on when the capacitor is charged, and has the same operation as the invention according to claim 7.

According to the tenth aspect of the present invention,
10. The AC converter in the electronic device according to claim 7, wherein one boost inductor to which a DC input voltage is applied is turned on and off to intermittently apply the DC input voltage to the boost inductor. And has the same function as the invention according to the seventh to ninth aspects.

The invention according to claim 11 according to the present invention provides:
The electronic device according to claim 10, further comprising control means for detecting a voltage change of a capacitor to which the current limiting means is not connected and controlling on / off operation of the switch means. It has the same function as the invention.

According to the twelfth aspect of the present invention,
12. The electronic device according to claim 11, further comprising a resistor connected between a high potential side terminal of the capacitor to which the current limiting means is not connected and a high potential side terminal of the capacitor to which the current limiting means is connected. It has the same function as the invention described in claim 11.

Hereinafter, embodiments of a DC-DC converter and the like according to the present invention will be described with reference to FIGS. (Embodiment 1) FIG. 1 is a main part electric circuit diagram showing an embodiment of a DC-DC converter according to the present invention and an electronic device incorporating this DC-DC converter. Are the same functional elements.

A portion X surrounded by a two-dot chain line in FIG. 1 shows an embodiment of the DC-DC converter according to the present invention.

The DC-DC converter X of the present embodiment
As is clear from the drawing, the structure of the rectifying / smoothing means 14 is different from that of the conventional example shown in FIG.

The rectifying / smoothing means 14 includes a series-connected body 7 in which a rectifying diode 9 and a capacitor 11 are connected in series as in the conventional example shown in FIG. 4, a rectifying diode 8 and a resistor 16 serving as current limiting means. And a capacitor 10 connected in series and different from the conventional example shown in FIG.
And 5.

In FIG. 1, when the transistor 3 of the AC converter 2 is turned on and off, the output voltage of the power supply battery 1 is intermittently supplied to the boosting inductor 4 as in the conventional example shown in FIG. An AC high voltage is generated at point A in the figure, which is the output terminal of the circuit.

The AC high voltage generated at the point A is supplied to the series-connected bodies 7 and 15 of the rectifying / smoothing means 14, so that the capacitor 10 is connected via the diode 8 and the resistor 16, and the capacitor 11 is connected via the diode 9. Charged.

The charging voltage of the charged capacitor 10 is:
Although the charging loop configuration is different, it functions as a drive power supply for the light source 12 by being directly supplied to the infrared light source (infrared light emitting diode) 12 without passing through the resistor 16 as in the prior art.

The charging voltage of the charged capacitor 11 is directly supplied to the infrared reflected light measuring circuit system (infrared reflected light measuring IC) 13 as described in the prior art, and the measuring circuit It functions as a drive power supply for the system 13.

When the light emitting operation of the light source 12 and the distance measuring operation by the measuring circuit system 13 are performed to perform the distance measuring operation,
As in the conventional example shown in FIG. 4, the charged charges of the capacitors 10 and 11 functioning as the respective power sources are consumed.

At this time, the potential at the point A is obtained by adding the voltage drop of the rectifier diode 8 to the terminal voltage of the capacitor 10 which is the potential in the conventional example shown in FIG. 4 without the resistor 16 as the current limiting means. A potential different from the potential V2,
That is, in the present embodiment, the resistor 16 is provided, and the rectifier diode 8 and the resistor 1 are connected to the terminal voltage of the capacitor 10.
The potential VA is higher than the potential V2 obtained by adding the voltage drop by the voltage V6.

Even when the performance of the power supply battery 1 is not sufficient such as when the performance of the power supply battery 1 is deteriorated at a low temperature, the potential at the point A becomes the potential VA described above.
In the present embodiment, a decrease in the potential at point A can be suppressed as compared with the prior art.

Therefore, in the present embodiment, the potential V at point A in the conventional example shown in FIG.
The charging operation can be resumed when the terminal voltage of the capacitor 11 drops below the voltage obtained by subtracting the voltage drop of the rectifier diode 9 from the potential VA at the point A higher than 2.

That is, in this embodiment, the capacitor 11 at the time when charging of the capacitor 11 is restarted
Is a voltage value higher than the terminal voltage value of the capacitor 11 by the voltage drop of the resistor 16 when charging is restarted in the conventional example having no resistor 16. In other words, the charging of the capacitor 11 is restarted in a state where the terminal voltage does not decrease significantly, and thus the fluctuation of the terminal voltage decreases, and as a result, the operation of the measuring circuit system 13 is not largely affected. The measurement circuit system 13 can operate stably.

As described above, in the embodiment of the present invention shown in FIG. 1, the potential at the point A is controlled by the extremely simple structure of the resistor 16 as the current limiting means in the case of the conventional example shown in FIG. Since the potential is controlled to be higher than that of the conventional example, the charging operation when the terminal voltage of the capacitor 11 decreases can be restarted at a higher level than in the conventional example.

As a result, the power supply operation to the measurement circuit 13 can be performed without greatly lowering the terminal voltage of the capacitor 11, and the measurement control circuit 13 can operate stably without malfunction. become.

Meanwhile, the terminal voltage of the capacitor 10 is expected to be lower than that of the conventional example. In such a case, the amount of light emitted from the light source 12 is reduced.

However, the decrease in the light amount of the light source 12 only shortens the distance to the farthest object that can be measured, and the distance measurement operation can be performed normally on the object within the shortened distance. This does not cause a major problem in the light source. In addition, even if the light amount of the light source 12 is prevented from decreasing, if the measurement circuit system 13 malfunctions, it does not make sense as the distance measurement operation. It is characterized by a configuration capable of preventing a malfunction of the measurement circuit system 13.

(Embodiment 2) FIG. 2 shows a DC-to-DC converter according to the present invention.
FIG. 9 is a main part electric circuit diagram showing another embodiment of a DC converter and an electronic device incorporating the DC-DC converter. In the drawing, elements having the same reference numerals as those in FIG. 1 indicate the same functional elements.

The portion X1 surrounded by a two-dot chain line in FIG.
Shows another embodiment of the DC-DC converter according to the present invention.

The DC-DC converter X1 of the present embodiment
As is clear from the drawing, the configuration of the rectifying / smoothing means 17 is different from that of the embodiment shown in FIG.

The rectifying / smoothing means 17 includes a series-connected body 7 similar to the embodiment shown in FIG. 1 in which a rectifying diode 9 and a capacitor 11 are connected in series, and a rectifying diode 8.
And a series-connected body 17 in which a control transistor 18 which is an active element functioning as a current limiting means and a capacitor 10 are connected in series.

The transistor 3 has a control electrode, whose base is connected to the measuring circuit 13, and a control signal output based on the detection result of the voltage detecting means of the capacitor 11 formed in the measuring circuit 13, for example. The operation is controlled by Specifically, the capacitor 11
When the terminal voltage is detected to be maintained at a desired voltage value, the transistor 3 is kept off, and when the terminal voltage is detected to be lower than the desired voltage value, the transistor 3 is turned on and off. The operation is controlled by a signal. It is needless to say that the control configuration itself of the transistor 3 can be applied to the embodiment described above with reference to FIG.

Since the present embodiment has the above-described configuration, the connection between the point A and the capacitor 10 can be switched by controlling the on / off operation of the control transistor 18. That is, the point A and the capacitor 10 can be connected by turning on the control transistor 18, and the point A can be disconnected from the capacitor 10 by turning off the control transistor 18.

Therefore, when the charge of the capacitor 10 is consumed, the control transistor 18 is turned off to disconnect the capacitor 10 from the point A, so that the point A is affected by the decrease in the terminal voltage of the capacitor 10 due to the consumption of the charge. You can avoid receiving.

As a result, the potential at the point A can be maintained at a high level, and even if the terminal voltage of the capacitor 11 decreases, a charging operation for compensating for the decrease can be performed quickly.

As described above, in the other embodiment of the present invention shown in FIG. 2, similarly to the above-described embodiment, the control transistor 18 which is an active element which functions as a current limiting means by using the potential at the point A as a current limiting means. Since the potential is controlled to be higher than that of the conventional example shown in FIG. 4 by a very simple configuration, the charging operation when the terminal voltage of the capacitor 11 drops can be performed at a higher level than that of the conventional example. Will be.

As a result, also in the present embodiment, the power supply operation to the measurement circuit system 13 can be performed without greatly lowering the terminal voltage of the capacitor 11, so that the measurement control circuit system 13 does not malfunction. It will operate stably.

In the case of the present embodiment, for the ON operation after the OFF operation of the control transistor 18, that is, for the recharging operation of the capacitor 10, a relatively large current as the charging current and a relatively long charging time are required. Since it is necessary, it is necessary to select a period during which the operation of the device is not adversely affected even if the terminal voltage of the capacitor 11 fluctuates, for example. Conversely, in a device having the above-described period, the control transistor 18 is turned on / off in response to the control sequence of the loads 12 and 13, so that the capacitor 1 is effectively used.
1 can be prevented from fluctuating, and a stable operation of the load 13 can be realized.

(Embodiment 3) FIG.
FIG. 10 is a main part electric circuit diagram showing still another embodiment of a DC converter and an electronic device incorporating the DC-DC converter, in which elements having the same reference numerals as those in FIG. 1 indicate the same functional elements.

The portion X2 surrounded by the two-dot chain line in FIG.
Shows still another embodiment of the DC-DC converter according to the present invention.

The DC-DC converter X2 of the present embodiment
As is clear from the drawing, is configured by connecting the high potential side terminals of the capacitor 10 and the capacitor 11 in the embodiment shown in FIG.

Further, similarly to the embodiment shown in FIG.
A control input of the DC-DC converter X2, that is, a control signal of the transistor 3 is obtained from the measurement circuit system 13 in which the capacitor 11 is a driving power source.
When the terminal voltage is detected to be maintained at a desired voltage value, the transistor 3 is maintained in an off state, and when the terminal voltage is detected to be lower than the desired voltage value, the transistor 3 is turned on and off. Has been made.

Therefore, in this embodiment, similarly to the embodiment described above with reference to FIG. 1, the power supply operation to the measurement circuit system 13 can be performed without greatly reducing the terminal voltage of the capacitor 11, and Thus, it is needless to say that a stable operation of the measurement circuit system 13 without malfunction can be realized.

Further, in this embodiment, the consumption of the charge of the capacitor 11 by the measuring circuit 13 is very small, and the terminal voltage of the capacitor 11 is maintained at a predetermined voltage value or more at which the operation of the measuring circuit 13 can be guaranteed. If so,
As a basic operation, the transistor 3 is kept off.

Here, consider a case where the terminal voltage of the capacitor 10 is abnormally lowered for some reason.

In such a case, the charging operation of the capacitor 10 is required for the next light emitting operation of the light source 12, but for example, the control resistor 19 in the present embodiment is not connected, and the capacitor 11 is connected as described above. If the terminal voltage of the capacitor 10 is maintained at a predetermined voltage value or higher, the transistor 3 remains off, the charging operation of the capacitor 10 is not performed, and as a result, the terminal voltage of the capacitor 10 remains abnormally low. However, if the next light emitting operation is performed as it is, the light emitting operation may be unnecessarily reduced.

However, in this embodiment, since the control resistor 19 is connected, when the terminal voltage of the capacitor 10 drops abnormally as described above, the charge of the capacitor 11 is transferred via the control resistor 19. The capacitor 10 is supplied to the
1 terminal voltage will be reduced.

When the terminal voltage of the capacitor 11 decreases, the decrease is detected by the measuring circuit 13 and the transistor 3
Is output from the measurement circuit system 13, in other words, the operation of the DC-DC converter X2 is restarted. As a result, both the capacitors 10 and 11 drive the respective loads. To a sufficient voltage value.

Thus, the capacitor 1 described above can be used.
It is possible to prevent the occurrence of inconvenience such as the terminal voltage of 0 being maintained abnormally low.

[0082]

According to the present invention, by connecting the current limiting means to the rectifying / smoothing means, the voltage fluctuation of the DC voltage output caused by the operation of the load receiving the DC output voltage is suppressed. Therefore, the power supply from the rectifying / smoothing means to which the current limiting means is connected is performed to the first load which is less affected by the voltage fluctuation and the like, and the power supply to the second load which is greatly affected by the voltage fluctuation and the like is supplied by the current. By using the rectifying / smoothing means to which the limiting means is not connected, it is possible to obtain a DC-DC converter capable of stably supplying power to the second load and an electronic device incorporating the DC-DC converter. have.

[Brief description of the drawings]

FIG. 1 is a main part electric circuit diagram showing an embodiment of a DC-DC converter according to the present invention and an electronic device incorporating the DC-DC converter.

FIG. 2 is a main part electric circuit diagram showing another embodiment.

FIG. 3 is a main part electric circuit diagram showing still another embodiment.

FIG. 4 shows a conventionally well-known DC-DC converter and its D-DC converter.
Principal electric circuit diagram showing an example of an electronic device incorporating a C-DC converter

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply battery 2 AC conversion means 3 Transistor 4 Step-up inductor 8,9 Rectifier diode 10,11 Capacitor 12 Light source 13 Measurement circuit system 14 Rectifying smoothing means 15 Series connection 16 Resistance 17 Rectifying smoothing means 18 Control transistor 19 Control resistor X, X1, X2 DC-DC converter

Claims (12)

[Claims] 1. An AC converter for converting a DC input voltage into an AC voltage and outputting the AC voltage, and a plurality of serially connected bodies in which a rectifier diode and a capacitor are connected in series. Rectifying and smoothing means for outputting a plurality of DC output voltages from each capacitor of the series-connected body, and in series with at least one rectifying diode of the plurality of series-connected bodies forming the rectifying and smoothing means, and the rectifying diode A DC-DC converter comprising current limiting means connected to a position where an output path for a DC output voltage of a capacitor connected in series with the capacitor is not formed. 2. The DC-DC converter according to claim 1, wherein the current limiting means is a resistor. 3. The current limiting means is turned off in response to an operation of consuming a charge of a capacitor connected to the current limiting means.
The DC-DC converter according to claim 1, wherein the DC-DC converter is a transistor that is turned on when the capacitor is charged. 4. The AC converting means comprises one boosting inductor to which a DC input voltage is applied, and switch means for turning on and off the switch to interrupt the application of the DC input voltage to the boosting inductor. The DC-DC converter according to claim 1. 5. The DC-DC converter according to claim 4, further comprising control means for detecting a voltage change of the capacitor to which the current limiting means is not connected and controlling on / off operation of the switch means.
DC converter. 6. A device according to claim 5, further comprising a resistor connected between the high potential terminal of the capacitor to which the current limiting means is not connected and the high potential terminal of the capacitor to which the current limiting means is connected. DC-DC converter. 7. An AC conversion means for converting a DC input voltage into an AC voltage and outputting the AC voltage, and a plurality of serially connected bodies in which a rectifier diode and a capacitor are connected in series. Rectifying / smoothing means for outputting a plurality of DC output voltages from each capacitor of the series-connected body, and in series with at least one rectifying diode of the plurality of series-connected bodies forming the rectifying / smoothing means, and the rectifying diode A DC-DC converter having a current limiting means connected to a position not forming an output path of a DC output voltage of a capacitor connected in series with the rectifying / smoothing means to which the current limiting means is connected; An electronic device connected to a first load that is less affected by the above. 8. The electronic device according to claim 7, wherein the current limiting means is a resistor. 9. The current limiting means is turned off in response to an operation of consuming a charge of a capacitor connected thereto, and
The electronic device according to claim 7, wherein the electronic device is a transistor that is turned on when the capacitor is charged. 10. The AC converting means includes one boosting inductor to which a DC input voltage is applied, and switch means for turning on and off the switch to interrupt the application of the DC input voltage to the boosting inductor. Claims 7 to 9
An electronic device according to claim 1. 11. The electronic apparatus according to claim 10, further comprising control means for detecting a voltage change of a capacitor not connected to the current limiting means and controlling on / off operation of the switch means. 12. A device according to claim 11, further comprising a resistor connected between a high potential terminal of the capacitor to which the current limiting means is not connected and a high potential terminal of the capacitor to which the current limiting means is connected. Electronic equipment.